Valve of explosion motors or internal combustion engines



Jan: 8, 1935. L, SANES 1,987,160

VALVE OF EXPLOSION MOTORS OR INTERNAL COMBUSTION ENGINES Filed Nov. 20,1930 Patented Jan. 8, 1935 VALVE oFExPLosIoN Morons on INTER- NALCOMBUSTION ENGINES Leon Saives, Billancourt, France, assignor to LouisRenault, Billancourt, France Application' November 20, 1930, Serial No.497,022 I In FranceDecember 11, 1920 2 Claims.

This invention relates to means whereby distribution of explosion motorsand internal com bustion engines provided with valves may be renderedperfectly silent and'smooth working by completely compensating for therelative expansions byheat of the cylinder, cylinderpassages, cameshaft,and thrust rods-or tappets, and thus allowing of the enginerunningwithan adjustment having unchangeable clearance; it further provides for,constructing camsopening and closingvery smoothly, whilststill keepingthe'points ofopeningandclosingfixed. .'I?he-;difiiculty toibe met; whichisespecially great in the case of the exhaust valves of such engines,resides in the fact that the temperature of each of .therparts'l of anengine does not 'depend: upon 5 a single variable accordingly as theengine cold, warm or hot; but upon several Variables. All the members donotheat up with I I have shown thatinstead of making with thewall jtheisameii-apidityaand the valve-heads and the bases of their spindlesfor example are more'sensitive to the condition of the engine thanto itsgeneral temperature; By taking into account "a second variable, whichfor example-will 'be the temperature:ofthe.head of the exhaust valvesthe "thermal state of the engine is defined in a very satisfactory way.1

The means which, according .to the invention, leads to the industrialresult sought, consists in determining the angle of the cone of contactof thevalve and of its seat by the conditions and methods, which will beexplai-ned. These means may be supplemented'ifnecessary by the additionof pieces of metal: more or less expansible by heat which are interposedin the award or constitute ,pa-rt i theusualmembers, such as valvespindle, thrust rod'and the like.

As stated above since the temperatures :of i the several members of theengineand especially of the members of the valve'mechanism cannotbesuitably determined except by making use of at 50 on the other hand,theduick'changes in the 1' compensating for the expansionof the top ofthe spindle I 7 Y Experience shows structed this rising of the valvehead is far from being suificient to compensate for the elongation ofthe spindles of theexhaust valves j inthe case of the admission valvesit much or too little According to the invention the angle of the coneof contact between the valve and its seat is increased from thatcustomary in the caseof the that in engines as now conis usually eithertoo exhaust valves so as to increase the rise of the valve head in itsseat under the action of the eripansions. In the case of the admissionvalves it is increased or decreased, according to circurn Experimentscarried outwith different angles of the explosion chamber an'angle 010(fiat valves) 30 or 45 corresponding to the shapes customarily used theseat of the'side exhaust valves ought to makes. much larger angle, whichmay exceed 60,whilst alwaysremaining below the angles at which-there isrisk of jamming, which approximate to 80,

I vUp to the present. time .in determining these importance.

The calculation hereinafter'described of the angle for each kind ofvalve-isbased upon'at least;= two series of precise measures of therelative expansions taken uponthe engine when runningunder varyingconditionsof temperature', and of temporary orcontinuous running, eachseriesot measures being taken with av-difier ent seatangle.

changes clearance in the valve stem, for exam- ;ple between the case ofthe completely cold engine, and that of the cold engine with hot valvesduring the first minutes of-starting under full load. This change notthe same in two series of measures taken with two difierent angles and Acompromise had been adopted bel In the first place observationis-made ofthe v the difference is proportional to the difference of r hot engine,uponiwhichthe angle acts in, proportion to its tangent, without alwaysgiving a perfect compensation.

In general it has been assumed that mass of the engine and the crankeasthe same temperature and expands degree; this assumption is not alwaysquite;aceurate and therefore it may be necessary .to; com" pletethearrangement by .theaddition of the in;- sert of one or more pieces ofmoreo'rless expansi ble metal, which, for example, is or are interposed"in the clearance space in the valve stem or which replace controlmembers and the sizes of which are easy at determine b'ytrialsandcalculations;

Such insertions arenecessary when the'di'sa tribution casing isof-alightnietatwhich does notexpand the same as the other parts of theen gineor when the operating means comprise rock ing levers which do notexpand inthe same way.

'Theplacing of inserts "is of course" necessary when the membersinvolved the engine-case and valve systemj are of metals having thes'ame co-eflicient of 'expa'nson, like cast iron and the majorityof-steels which-heat equallyjand simul- The accompanying two-figures ofdrawing will explain the operation of-the arrangementin thiscasein-particular, in which g "Figure 1 is a sectional view' showing aportion of an internal-combustion engine case, i valvei-and valveoperating mechanism, and

Figure 21 a detail oi 'a valve head-illustrating its expansion on alarge scaleon'which"- the-cal-' culations are based. I, In the firstplace it must bea'ssumed that the head 10f thevalve and the top 2 of thestem u'p to thegeometri'c'al apex ofthe cOne are "at an identicalvariable temperature/t that the cylinder and thecasings-lj the'carn- 5;the thrust rods or rocking levers together with the adjustingmembers,"rods and tappets fi andthe stem 7 of the'valve, all having thesame co-efficient ofexpansion, are at an identical variable tempera Itis understoo that if each of these two aggregates at independenttemperatures t and t remaining constant, the cone of the seatj and theconefot the valve keeptheir angle and continue coincident-because thediameter of the valve will 1.

V 'vary in proportionfto compensate for'the 'lift of thevalve off itsseat due to ex-pansion in the Thefhead of the valve is the-part whichis-sub?- jected to the highest'temperature (t whilst the top of thevalve-rod is at a lower'temperature; and

the bottom of this rod at a stilllower one (t Under the action of thesetemperatureswhich are distributed gradually along the valve andits rod,the "valve is of a different-length from that which it would have if itwerethr'ou'ghout at the temperature t Its elongation has a certain valueand itis easy to calculate thelengthoi a bar of the same metal which ifheated from thetemperature t2 to'the temperature t would give the sameelongation as the valve. This lengthof'the bar is bar belowthe level ofthe valve-seat. It follows from the above definition of the point 3 thatthe elongation of the valve is the same asii it were at thetemperaturefl from the head'tothe point 3 and at the temperature itbelow the point 3. It is clear that for all temperatures t thedistribution of temperature from the top to the bottom of thevalvejtakesmlace similarly and that, all the elon- *gations of "thevalvebeing equaL'the so -called rnean point} will remain in the sameplace. I

; Theinvention consists in taking, as apex of the cone formed by thehead of the valve and by its seat, thejrnean point 3; if this is done asshown in"the"accompanying drawing, the respective ex- 1 pansionsi willbe compensated.

Obviously points 3 do not really exist at which the temperature-of thevalve changes suddenly from onevaluet to another value it, but it isunderstood that there isa middle point such that, with'res'pect to 1 andt the insufiiciency of temperature on a one side compensates for theexcess of temper'atureonthe other. The expansion of the part or thespindle where the progressive change of temperature takes place isassumed the same'as if there were 'a clear division in the distributionof the temperatures, as indicated at the point 3,-thediiference inhatching ofthe movable valve member above and belowthe point- 3 beingfor the purpose ofrepresenting' the two'temperatures'i andtof the parts.'Valvestem 7 is nec of the same; material and have the same coeflicienttangent for which the change of clearanceis null.

For a better understanding, reierenceismade .toFigure 2.01 thedrawingwherein the cold valve was shown incontinuous lines, and, the hotvalve .in interrupted lines; -.a is the angle of, the; valve .seat;.EBis theradius r of thevalve plate when said valve is cold. .Whenthevalve .is hot, its

radius increases and. becomes. F D= r+dr; this increase has for resultaliftinggofthe valve of,

the height j" o f=fqn amear V However,;at the. same time, the increaseoi valve temperature has for eflectan increase A of the :rod belowtheypoint E. It results that the differ ence betweenf the clearancein=the case ofa cold valve and theclearance in the case of a hot valveis 'H=,Adrqtan;a, whatever is the angle a. An.

experiment was made with an angle a1=30 -(which corresponds to an angleof 120' at the top ,of the cone constituting the valve seat) and asecond experiment was made. with an angle (12:67

30' (which'corresponds to an angle of 45 atthe' top of the coneconstituting the valve seat).

In'theflrstcase ,(anglc it was found that the difierence of clearancewas H1 0.22 mm.) in the second case (angle 1x 2) it was found that thedifference of clearance wasonly H2=0L065 mm.

"other angle a such that-A-drtan a==0.

For, having H=0, it is necessary to choose an- For the three equationsAdr tan :0, 22. A-dr tan 67 ao'=o, 065. Adr tan 1:0.

It is easy to determine a after having eliminated A and dr. It can thusbe found that a must be 63 20'.

In practice the diameter of the valve head is given preliminarily anddependsupon the type of the engine because the constructor knows that,for a given engine, it is necessary to choose a valve head having adetermined diameter in order to ensure a suitable passage-way for asatisfactory flow of gas when the valve is open. On the other hand, itis to be noted that the point 3 is on the stem substantially below thehead and that, for this reason, the angle of the valve seat variesrather little when the head diameter is comprised between usual limitswith respect to the stem length. Practically, whatever is the headdiameter, said angle is more open than in known valves.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, I declare thatwhat I claim is:'

1. In an internal combustion motor, the combination with the motorcasingof a valve and its stem each having cooperating conical seatingsurfaces wherein the surfaces are generated from a cone the apex ofwhich is located centrally of the stem and determined by the point ofdifierence in expansion of the valve head with the portion of the stemadjacent thereto and thelower portion of said stem.

2. In an internal combustion motor the combination with the motor casingand valve operating mechanism of a valve and its stem cooperatingtherewith, said casing and valve head having cooperating conical seatings'urfaces generated by a cone of such dimensions as to compensate forthe difference in expansion of the valve and stem member and the casingand valve operating mechanism so as to permit the proper seating of thevalve on the casing seat at all temperatures of the motor withsubstantially the elimination of clearance between the valve stem andvalve operating mechanism, such generating cone having its apex locatedcentrally of the stem and determined by the point of difference inexpansion of the valve head with the portion of the stem adjacentthereto, and the lower portion of said stem.

LEON SAIVES.

